TABLE 2.1 The Elements of Life* Atomic Approximate Element Symbol Number Atomic Weight Hydrogen H 1 1 Carbon C 6 12 Nitrogen N > 14 Oxygen 0 0 16 Sodium Na 11 23 Magnesium Mg 12 24 Phosphorus P 15 31 Sulfur s 16 32 Chlorine CI 17 35 Potassium K 19 39 Calcium Ca 20 40 Iron Fe 26 56 lodine 53 127 *Hydrogen,carbon,nitrogen,and oxygen are the most abundant chemical elements in living organisms. Table 2.1Table 2.1